Essential Concepts of Radiologic Science

Vocabulary practice flashcards covering fundamental concepts of matter, forms of energy, electromagnetic and ionizing radiation, and sources of natural and human-made radiation from Chapter 1 of Radiologic Science for Technologists.

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Matter

Anything that occupies space and has mass; it composes physical objects, is made of atoms and molecules, and possesses form and shape.

Mass

The quantity of matter contained in a physical object, which remains constant throughout the universe.

Kilogram ($\text{kg}$)

The base scientific unit of measurement for mass in the SI system.

Energy

The ability to do work.

Joule ($\text{J}$)

The SI unit of measurement for energy.

Electron Volt ($\text{eV}$)

The unit of measurement used for energy in radiology.

Potential Energy

Energy stored in an object by virtue of its position.

Kinetic Energy

Energy possessed by an object due to its motion.

Chemical Energy

Energy released by a chemical reaction.

Electrical Energy

Energy produced when an electron moves through an electrical potential difference (voltage).

Thermal Energy

The energy of motion at the molecular level, commonly known as heat.

Nuclear Energy

Energy contained within the nucleus of an atom.

Electromagnetic Energy

The type of energy used in x-ray imaging consisting of electric and magnetic fields traveling through space in waves as bundles called photons.

Photons

Bundles of electromagnetic energy that travel through space in waves.

Mass-Energy Equivalence ($E = mc^2$)

The equation stating that energy ($E$) equals mass ($m$) multiplied by the velocity of electromagnetic radiation in a vacuum ($c$) squared, establishing that matter can be transformed into energy.

Radiation

Energy emitted and transferred through space.

Irradiated (Exposed)

The state of matter that has intercepted radiation.

Ionizing Radiation

A special type of radiation capable of removing an orbital electron from an atom with which it interacts.

Ion Pair

The resulting combination of an ejected free orbital electron (negative ion) and the remaining atom with a net positive charge (positive ion) following an ionization event.

Ubiquitous Background Radiation

Natural environmental radiation consisting of cosmic rays, terrestrial radiation, internally deposited radionuclides, and radon, delivering an average annual dose of approximately $3.1\,\text{mSv}$.

Cosmic Rays

Particulate and electromagnetic radiation emitted by the sun and stars, whose intensity on Earth increases with altitude and latitude.

Terrestrial Radiation

Background radiation emitted from deposits of uranium, thorium, and other radionuclides in the ground, whose intensity depends on geological area.

Internally Deposited Radionuclides

Natural sources of radiation that enter the human body via ingestion or inhalation, mainly consisting of potassium-40 ($^{40}\text{K}$).

Radon

The largest source of natural background radiation; a radioactive gas produced by the radioactive decay of uranium that emits alpha particles.

Medical Radiation

The largest human-made source of ionizing radiation, predominantly contributed by computed tomography ($63\%$) and nuclear medicine ($15\%$).